@dmbe11 Monitor 0 will be triggered because the temperature reached 312 and I expect the maximum heater temperature command is on the default (290C)
https://docs.duet3d.com/User_manual/Reference/Gcodes#m143-maximum-heater-temperature
That said the issue is you have 40+C overshoot during tuning which is so much that the tuning algorithm throws an error
The M303 command does not have a setting to allow for a wider range as far as i can see:
https://docs.duet3d.com/User_manual/Reference/Gcodes#m303-run-heater-tuning
You can try tuning with a lower PWM (e.g. setting the P parameter to 0.7 or 0.5) however presumably you have such a high power heater because you are going for extremely high flow rate so you need the full 70W when extruding fast?
Maybe @dc42 has a suggestion on how to tune in this scenario.
